1. Technical Field
The present disclosure generally relates to a piezoelectric microfluidic pumping device.
2. Description of the Related Art
Piezoelectric materials are useful for actuating electromechanical devices. Piezoelectric materials are those that exhibit both a piezoelectric effect and a reverse piezoelectric effect. The piezoelectric effect is the generation of a voltage across opposite faces of a piezoelectric material in response to applying pressure to the piezoelectric material. The reverse piezoelectric effect is the contraction, expansion, or otherwise deformation of a piezoelectric material in response to applying an electric field across the piezoelectric material. Some approaches to pumping liquid utilize the reverse piezoelectric effect for actuation.
U.S. Pat. No. 6,294,860 (hereinafter '860 patent) describes an ink jet recording device equipped with a piezoelectric film element. The recording device includes a vibrating plate with a piezoelectric film placed over an ink reservoir formed in a first substrate. The vibrating plate creates pressure within the ink reservoir causing ink to eject from the ink reservoir. The ink reservoir is formed by entirely removing a portion of the first substrate located directly beneath the piezoelectric film. Ink is ejected from the ink reservoir through an ink jetting nozzle formed in a second substrate that is bonded to a lower surface of the first substrate so that the nozzle jets ink in a direction that is away from the piezoelectric film.
Japanese publication JP2003133604 describes an ink jet recording device that is similar to '860 patent with the exception that a nozzle is formed in a plate that is thinner than the second substrate of the '860 patent, however, similar to the '860 patent the thin plate is bonded to the bottom of the first substrate.
The existing approaches appear to be limited to pumping liquid in a direction that is away from the piezoelectric element out of a reservoir that extends completely through a substrate that is below the piezoelectric element.